The present invention relates to three-dimensional (3D) imaging. More particularly, the present invention relates to methods for efficiently manipulating 3D scenes.
Throughout the years, movie makers have often tried to tell stories involving make-believe creatures, far away places, and fantastic things. To do so, they have often relied on animation techniques to bring the make-believe to “life.” Two of the major paths in animation have traditionally included, drawing-based animation techniques and physical animation techniques.
Drawing-based animation techniques were refined in the twentieth century, by movie makers such as Walt Disney and used in movies such as “Snow White and the Seven Dwarfs” (1937) and “Fantasia” (1940). This animation technique typically required artists to hand-draw (or paint) animated images onto a transparent media or cels. After painting, each cel would then be captured or recorded onto film as one or more frames in a movie.
Physical-based animation techniques typically required the construction of miniature sets, props, and characters. The filmmakers would construct the sets, add props, and position the miniature characters in a pose. After the animator was happy with how everything was arranged, one or more frames of film would be taken of that specific arrangement. Physical animation techniques were developed by movie makers such as Willis O'Brien for movies such as “King Kong” (1933). Subsequently, these techniques were refined by animators such as Ray Harryhausen for movies including “Mighty Joe Young” (1948) and Clash Of The Titans (1981).
With the wide-spread availability of computers in the later part of the twentieth century, animators began to rely upon computers to assist in the animation process. This included using computers to facilitate drawing-based animation, for example, by painting images, by generating in-between images (“tweening”), and the like. This also included using computers to augment physical animation techniques. For example, physical models could be represented by virtual models in computer memory, and manipulated.
Computer animation techniques are also applied to 3D images or scenes. 3D imaging is creating the illusion depth in an image or scene. Depth perception is created in the brain by providing the eyes of the viewer with two different images (left and right), representing two images of the same object, with the deviation similar to the minor difference between the image perceived by a viewer's left eye and the image perceived by a viewer's right eye.
One means of presenting different images to the two eyes is color filter glasses, for example the red/cyan anaglyph. In this scheme, one eye (e.g., left eye) views a scene through a red filter and the other eye (e.g., right eye) views a scene through a cyan filter. The scene includes portions in red and portions in cyan—red and cyan being chromatically opposite colors—such that both eyes perceive different images to create the illusion of depth. This scheme with it's low-cost cardboard glasses is commonly known due to its use dating back to 3D comic books in the 1950s and is enjoying a resurgence due it's use in 3D films released on DVD and Blu-ray Disc™.
Well-known drawbacks to using color filter glasses include that since each of the two-dimensional images are monochromatic, the three-dimensional image is also monochromatic, and not in full color. Another drawback is that by using a color filter or gel, the two-dimensional images provided to the viewer's eyes tend to be darker due to the filtering-out of colors.
Shuttered glasses typically include electrical or mechanical shutters that sequentially open and close to alternatively present right-eye images and left-eye image to a viewer. In such systems, a display alternatively displays a right-eye image and then a left-eye image, such that when the right-eye shutter is open, the viewer sees the right-eye image on the display, and when the left-eye shutter is open, the viewer sees the left-eye image on the display. A benefit of this technique includes that a single projector or display can be used to display both the right-eye image and left-eye image. Another benefit is that the perceived three-dimensional image can be in full color.
Drawbacks to such a scheme includes that the viewer must wear relatively costly glasses that have a mechanical or electronic shuttering mechanism. Furthermore, the glasses must include a mechanism to allow the shutters to be electronically synchronized to the appropriate fields of the display. Another drawback is that viewers sometimes report discomfort as the images flicker on the display.
Another means of presenting different images to the two eyes is polarized glasses. The left-eye images and right-eye images displayed to viewers are typically polarized using different polarization schemes, and the polarized glasses are also polarized in the same manner. Linear polarization may be used. In this scheme, two images are projected onto a screen through orthogonal polarizing filters. The projectors may receive their output from a computer, which generates the two images. The viewer views the scene through eyeglasses containing a pair of orthogonal polarizing filters. The viewer's eyes perceive two different images, because each filter allows only similarly polarized light through and blocks orthogonally polarized light. Linearly polarized glasses require that the viewer keep his or her head level, because tilting the viewing filters causes the left and right images to bleed into the other.
Circular polarization may also be used. As an example, a right eye image is polarized using a counter-clockwise circular polarization and displayed to the viewer, and at the same time, the left eye image is polarized using a clockwise circular polarization and displayed to the viewer. Because the right eye of the viewer's glasses have a polarization filter that transmits counter-clockwise circular polarized light, and the left eye of the viewer's glasses have a polarization filter that transmits clockwise circular polarized light, the left image is delivered to the left eye, and the right image is delivered to the right eye.
Both polarizing schemes have the benefit of relatively low cost pair of glasses to view such images. Additionally, the perceived three-dimensional images are in color. However drawbacks to such techniques include that two projectors are required to display the two images, each having different polarizations.
While viewing 3D images, the user may wish to manipulate the images by changing parameters of a virtual camera recording the images. For example, the user may wish to change the position of the camera in 3D space, aperture, lens, focus, focal length, field of view, and the like.
While wearing filtering glasses and operating a computer system to manipulate 3D images, it is challenging to keep the user focused on the screen at all times. The user may take off the glasses to operate the computer system, tilt the head to look at a computer output device (e.g., monitor), or tilt the head to look at a computer input device (e.g., keyboard and mouse). Each time, the viewer takes his or her eyes off the display and must reorient his or her head to resume viewing the scene, resulting in a loss of precious time.
Accordingly, what is desired are methods that address the problem described above.